Updated example on wire dipole model.

docs/source/examples_antennas.rst

@@ -4,25 +4,22 @@ Antenna models
 
 This section provides some example models of antennas. Each example comes with an input file which you can download and run.
 
+.. _example-wire-dipole:
+
 Wire dipole antenna model
 =========================
 
-**INFO ON THIS MODEL IN PROGRESS**
-
 :download:`antenna_wire_dipole_fs.in <../../user_models/antenna_wire_dipole_fs.in>`
 
-This example demonstrates a model of a half-wavelength wire dipole antenna in free space. The length of the dipole is 150mm with a diameter of 6mm, and a 1mm gap between the arms.
+This example demonstrates a model of a half-wavelength wire dipole antenna in free space. It is a balanced antenna and it's characteristics are well known from theory _[BAL2005]. The length of the dipole is 150mm with a 1mm gap between the arms.
 
 .. literalinclude:: ../../user_models/antenna_wire_dipole_fs.in
     :language: none
     :linenos:
 
-.. figure:: images/antenna_wire_dipole.png
-    :width: 600 px
+The wire is modelled using the ``#edge`` command which specifies properties of the edge of the Yee cell. The antenna is fed using the ``#transmission_line`` command. The one-dimensional transmission line model virtually attaches to the dipole at the gap between the arms. The antenna has an input impedance (:math:`Z_0`) of 73 Ohms specified in the ``#transmission_line`` command, and uses a Gaussian waveform with a centre frequency of 1GHz.
 
-    FDTD geometry mesh showing a wire dipole antenna model.
-
-The antenna is fed using the ``#transmission_line`` command. The one-dimensional transmission line model virtually attaches to the dipole at the gap between the arms. The antenna has an input impedance (:math:`Z_0`) of 73 Ohms specified in the ``#transmission_line`` command. The transmission line uses a Gaussian waveform with a centre frequency of 1GHz.
+Time histories of voltage and current values in the transmission line are saved to the output file. These are documented in the :ref:`output file section <output>`. These parameters are useful for calculating characteristics of the antenna such as the input impedance or S-parameters. gprMax includes a Python module (in the ``tools`` package) to help you view the input impedance and admittance and s11 parameter from an antenna model fed using a transmission line. Details of how to use this module is given in the :ref:`tools section <plotting>`.
 
 Results
 -------
@@ -31,15 +28,15 @@ Results
 
 .. figure:: images/antenna_wire_dipole_fs_tl_params.png
 
-    Time and frequency domain plots of the incident and reflected (scattered) voltages in the transmission line.
-
-Explanation of figures.
+    Time and frequency domain plots of the incident and total (incident + reflected) voltages and currents in the transmission line.
 
 .. _antenna_wire_dipole_fs_ant_params:
 
 .. figure:: images/antenna_wire_dipole_fs_ant_params.png
 
-    s11 parameter and input impedance (resistance and reactance) of the antenna.
+    Input admittance and impedance (resistance and reactance) and s11 parameter of the antenna.
+
+:numref:`antenna_wire_dipole_fs_tl_params` shows time histories and frequency spectra of the incident and total (incident + reflected) voltages and currents in the transmission line. :numref:`antenna_wire_dipole_fs_ant_params` shows the input admittance and impedance (resistance and reactance), and s11 parameter of the half-wavelength wire dipole. The s11 parameter shows that the antenna is resonant at 1GHz which is what is expected from the geometry and feeding. The input resistance (the real part of the input impedance) is 73 Ohms which is what is predicted by theory. The input reactance (the imaginery part of the input impedance) is a function of the length of the dipole and is zero in this case.
 
 
 Bowtie antenna model